The following system has been proposed as this type of conventional example. The system comprises a recording medium for distribution such as CD-ROM on which encrypted digital contents are recorded, management means for managing charges in accordance with the use of the digital contents by a user, a digital contents reproducing device which is used when the digital contents are reproduced by the user who has acquired the recording medium for distribution, and which can be connected to the management means via an internet line. A basic configuration of the system is such that when an application for digital contents is inputted to the digital contents reproducing device by the user under the condition of authentication and billing, the digital contents reproducing device transmits the application to the management means via the internet line, and the management means, after confirming authentication and billing of the user relating to the relevant application, transmits a decryption key data to the digital contents reproducing device via the internet line, and the digital content reproducing device decrypts the digital contents on the recording medium for distribution by using the decryption key data to reproduce it (for example, refer to Patent Document 1 or the like).
Patent Document 1: Japanese Published Unexamined Application No. 2002-334172.
However, in the case of the above-mentioned conventional example, in the digital contents reproducing device, once the digital contents on the recording medium for distribution is decrypted, not only the reproduction but also copy can be performed easily, so that it has an essential drawback that secondary illegal use cannot be prevented.
However, while the secondary illegal use can be prevented if there is added a function of automatically deleting the digital contents after a predetermined period of time from a reproduction application has passed, there arises another drawback that the collection of charges in accordance with the secondary use cannot be expected any longer.
This problem is not specific to the case where digital contents are distributed to a user through a recording medium for distribution, but there is a similar problem in the case where the digital contents are delivered through an Internet line or the like. Namely, profits that a contents holder or the like should obtain under normal circumstances are illegally lost, and in this regard, the distribution of the digital contents is impeded from being promoted under the present situation.
The present invention is created under the above-described background, and a first object of the present invention is to prevent illegal use of data (digital contents) and a second object is to provide a method for processing the data in which the collection of charges in accordance with secondary use of the data can be surely performed, a data reading method for reading the data processed by this processing method, and a recording medium on which programs implementing these methods are recorded.